1. Field of the Invention
The invention relates to an electromagnet, in particular an electromagnet intended to actuate the switches of a contact-maker apparatus, comprising:
a fixed yoke, a movable armature which is connected to these switches and which comprises a core concentric with an energization coil, as well as at least one magnetizable plate separated from the yoke by a variable longitudinal air-gap; PA1 a return means which cooperates longitudinally with the armature for conferring thereon a rest position when the coil is de-energized, and PA1 a concentric compensation spring disposed in an external region of the yoke opposite this air-gap, and whose forces antagonistic to this return means are only exerted over a fraction of the travel of the armature.
2. Description of the Prior Art
Such an electromagnet, which may be illustrated by the French Pat. No. 2 573 567 of the Applicant, is in particular applicable to small contact-makers, respectively automatic device relays, and has no means for progressive adjustment of the initial force of this compensation spring or its resilience.
The provision of an adjustment means is however desirable to the extent that it allows adaptation to the inevitable dispersion of the resilient properties which the return means may provide whereas its presence may also be used to guarantee that the electromagnet will operate cleanly when its coil is fed with the control voltage in a given environment.
Furthermore, the presence of a resilient compensation member or device may be necessary when the number of switches operatively opening and/or closing is not known beforehand.
The invention proposes consequently adding to an electromagnet such as defined above a compensation device of great simplicity offering an extended facility of progressive adjustment.